Streetcar heating system



Feb. 18, 1 941. I c, BRANDT I I 2,232,587

STREETCAR HEATING SYSTEM Filed Sept. 26. 1938 {inventor Ffiederick C-Brandt Patented Feb. 18, i941 UNITED STATES PATENT OFFICE STREETCAR HEATING SYSTEM Frederick C. Brandt, Chicago, Ill., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn-, a corporation of Delaware Application September 26, 1938, Serial No. 231,705

4 Claims. (Cl. 237-5) This invention-reiates in general to air condltion and ,to the accompanying drawing in which: tioning, and is more particularly concerned with Figure 1 is a fragmentary sectional view of a heating and ventilating arrangements for vehistreet car having my invention applied thereto, cles such as-streetcars. Inheatlng of streetcars and in which 5 it has become common to utilize heated air Figure 2 is a sectional. view :taken at right 5 which is heated by passing it over a group of angles to Figure 1. resistors which act as starting resistance for the Referring to the drawing, reference characcar motors when the car is being started, and ter I indicates the floor of a streetcar having which act as a load for the car motors for formside walls 2 and 3 and a roof 4. Located being a generative braking-system fol-decelerating neath the roof I is a ceiling 5 which is spaced the car. This arrangement provides for utillzfrom the roof to provide an air passage 6, this ing energy which would otherwise be wasted for air passage communicating with the passenger heating the car. However, this arrangement respace through grills 1 and 8.

quires that air be passed over the resistors at Extending along the length of the car adjaall times in order to avoid burning out the recent the side wall 2 and beneath the seats is a 15 sistors. In order to control the temperature discharge duct 9 which is provided with grills in the car, it has heretofore been usual practice ll through which heated air is discharged into to utilize a thermostatically controlled diverting the passenger space. A similar return duct ll damper which varies the proportions of the is provided adjacent the side wall 3. Located 30 heated air supplied to the'car and discharged to beneath the floor I is a conditioning chamber I2, atmosphere. While systems of this type functhe righthand end of which is connected to the tion satisfactorily during cold weather when discharge 0! 8 fan The inlet of fan is heat is constantly required, they do not provide connected to an inlet duct it which in turn is for maintaining proper temperature conditions connected by a duct l5 leading from the return in the car during mild weather. During mild air duct H and'to a fresh air inlet IS. The pro- 25 weather such as when outdoor temperature is at portions of fresh and return air supplied to the 45 F. or above, it often becomes necessary to conditioning chamber l2 are controlled by supply cool air to the car instead of heated air, means of dampers l1 and i8. due to the heating effect of the sun and due to Located within the conditioning chamber l2 the heat given off by the occupants. is a group of resistance heaters I9 which are con- 30 It is an object of this invention to provide a nected into the driving motor control circuit, heating system of this general type for heating these resistance heaters acting as starting restreet cars or other vehicles which not only sistances for the car motors, and also as'a load automatically controls the supply of heat to the for the motors which act as generators when the car, but also supplies just the prope amount of car is being decelerated. Also located within cool outside air to the car when cooling is reconditioning chamber I2 is a partition 20 which quired. provides a by-pass 2| for the air around the More specifically, it is an object of this invenheating elements l9. This by-pass 2| is contion to provide a system of this type which pronected by a duct 22 to the space 8 between the a 40 vides for introducing the cooling air to the space roof 4 and the ceiling 5. The passage contain- 40 in a manner to avoid chilling the occupants of 1118 the at E e I9 is Connected y a the car. duct 23 to the discharge duct 9.

Another object of this invention is the pro- The flow of air through the duct 22 to the ceilvision of a heating and cooling system which ing'g lls is co trolled y means of a -D supplies heated air near the floor line of the located within the by-pass 2|. The flow of heat- 45 space being heated for thereby maintaining the ed air to the discharge duct 9 is controlled by floor and the occupants feet warm. while supmeans of a-damper 25 located on the downstream plying cool air above the floor line, the proporside of the heating elements 19. This damper 25 tions of heated and cool air supplied being autois pivoted at 28 adjacent an opening 21 in the matically varied in a manner to maintain the wall of the conditioning chamber i2. It will be 50 desired temperature within the space. apparent. that when damper 25 is in the position Other objects will appear from the following shown, no heated air will be supplied .to the disdescription and the appended claims. charge duct 9 and this heated air will pass through For a full disclosure of this invention, referthe opening 27 toatmosphere. This provides for 65 ence is made to the following detailed descripcooling the resistance elements l8, thus Dreventing such elements from burning out when no heat is required within the space. As damper II is rotated in a clockwise direction, it wilideorease the portion of the air through opening 21 and increase the portion of air supplied to the discharge duct I. This damper 25 is actuated by means of a motor II under the control of a thermostat 2| located within the car. The motor II and thermostat 2! may be of any suitable tyvpe and are preferably of the pneumatic type receiving air from the car compressed air braking system. The damper 25 is also connected by means of a cross-connection 3| to the by-pass damper 24. This arrangement causes the bypass damper 24 to open as the damper 25 rotates in a counter-clockwise direction.

With the parts in the positions shown, the term perature within the car is above the control point of thermostat 2! which has caused this thermostat to position the damper 25 in a manner to stop flow of heated air to the discharge duct I. This has caused the by-pass damper 38 to be wide open. A mixture of the fresh and return air is now being supplied to the conditioning discharging of cool air into the passenger space at the ceiling will cause cooling of, the car while at the same time avoiding discomfort to the passengers.

As the temperature within the car decreases, the thermostat 29 will shift the dampers 2i and 25 in a manner to decrease the flow of cold air through the grills I and 8 and to permit flow of heated air into the space through the grills Ill. When the space temperature falls below the control point of thermostat 29, the damper 24 will be closed for preventing any unheated air from passing to the space and the damper 25 will be positioned for passing all of the air leaving the heating element I! to the car.-

From the foregoing description, it will be apparent that during all times fresh air for ventilation purposes will be supplied to the car, this air being heated and supplied to the interior of the car at the floor line for heating the car when heat is required. When cooling is required, the supply of heated air adjacent the floor line is discontinued and instead unheated air is supplied at the ceiling for thereby cooling the passenger space. For intermediate values of temperature, the proportions of heated and cooled air supplied to the space will be varied by the thermostat 2! in a manner tending to maintain the temperature constant. This feature is quite important in the heating of street cars, for the supplying of warm air at the floor line provides for maintaining the car floor and the passengers feet warm. Due to the simultaneous supplying of cool air at the celling, considerable warm air may be supplied at the floor line without overheating the car. My

improved system therefore permits the supplying of warm air to the car for maintaining the passengers feet and legs comfortable at times when no heat is necessary for maintaining the desired temperature, overheating of the car being avoided by supplying the proper amount of cooling air at the ceiling. Also my improved system provides for actually cooling the car when cooling is re-- quired by automatically reducing or interrupting the flow of heated air, and increasing the supply of unheated air.

While my invention is of special utility for heating street cars, it will be apparent that it is not limited to this specific applicaton and may be used on other types of vehicles and even in stationary applications. Also, while I'have shown the dampers I4 and 25 as being actuated in unison by a single motor, these dampers may be provided with separate motors and in some cases may be actuated in sequence so that the supply of heated air is entirely stopped before cool air is introduced to the space being conditioned. The principles of this invention are also applicable to other than heating systems and may be used in cooling systems as well. As many modifications which are within the scope of my invention will occur to those skilled in the art, I desire to be limited only by the scope of the appended claims.

I claim as my invention:

1. In an air conditioning system for a space, in combination, a conditioning chamber including a heating means for heating air passing therethrough, a fan connected to the inlet of said conditioning chamber for forcing air through said chamber, lower duct means for conveying air from said heating means to said space and for discharging said air into said space at a relatively low level, an outlet for heated air from said conditioning chamber, damper means associated with said lower duct means and said outlet in a manner to vary the proportions of heated air passed through said lower duct means and through said outlet, a by-pass for air around said heating means, upper duct means for conveying substantially only air from said by-pass to said space and for discharging said air into said space at a higher level, damper means for controlling the flow of by-passed air to said space, and thermostatic means responsive to the demand for heat for controlling both of said damper means. said thermostatic means acting upon rise in space temperature to decrease the flow of air through said lower duct means and to increase the flow of air through said upper duct means.

2. In an air conditioning system for a space, said space having a lower portion for human occupancy and an upper portion above said lower portion, a mixing chamber, means including fan means for causing return air from said space and fresh air to now into said mixing chamber, a lower duct means for discharging air into the lower portion of said space, upper duct means for discharging air into the upper portion of said space, a heater, means for passing a portion of the mixture of fresh and return air into contact with said heater and to said lower duct means; means for passing another portion of said mixture to said upper duct means without contacting said heater, first control means for controlling the flow of air through said upper duct means, second control means for controlling the effect of said heater upon said space, and thermostatic means for controlling said first and second control means, said thermostatic means acting upon rise in temperature to reduce the effect of said heater and to increase graduatingly the flow of air through said upper duct means.

3. In an air conditioning system for a space, said space having a lower portion for human occupancy and an upper portion above said lower portion, a mixing chamber; means including fan means for causing return air from said space and fresh air to flow into said mixing chamber, a lower duct means for discharging air into the lower portion of said space, upper duct means for discharging air into the upper portion of said space, a heater, means for passing a portion of the mixture of fresh and return air into contact with said heater and to said lower duct means,

means for passing another portion of said mixture to said upper duct means without contacting said heater, first control means for controlling the flow of air through said upper duct means,-

seco ld control means for controlling the flow of heated air through said lower duct means, an outlet for heated air from said chamber, said outlet being associated with said lower duct means and said second control means so that the proportions of heated air passed through said lower duct means and said outlet will be controlled by said second control means, and thermostatic means for controlling said first and second control means, said thermostatic means acting upon rise in temperature to reduce graduatingly the flow of heated air into said lower duct means and to increase graduatingly the flow of air through said upper duct means.

4. In an air conditioning system for a space, said space having a lower portion ior human occupancy and an upper portion above said lower portion, a mixing chamber, means including fan means for causing return air from said space and fresh air to flow into said mixing chamber, a lower duct means for discharging air into the lower portion of said space, upper duct means for discharging air into the upper portion of said space, a heater means for passing a portion of the mixture of fresh and return air into contact with said heater and to said lower duct means, means for passing another portion of said mixture to said upper duct means without contacting said heater, control means for controlling the flow of air through said upper duct means and the effect of said heater upon said space, and thermostatic means for controlling said control m e ans, said thermostatic means acting upon rise in temperature to reduce the effect of said heater and to increase graduatingly the flow of air through said upper duct means.

FREDERICK C. BRANDT. 

